Effect of PU.1 deficiency on TLR4 expression in WT, PU/ER(T)^+/−, and PU/ER(T)^+/+ bone marrow chimera mice. (A) BAL macrophages were collected from WT, PU/ER(T)^+/−, and PU/ER(T)^+/+ bone marrow chimera mice on the 45th and 55th day (before and after clearance of circulating tamoxifen), and then total RNA was isolated. Expression levels of TLR4 were measured by qRT-PCR. Data are representative of the average of measurements from 4 different mice. (B) Total RNA isolated as described in panel A was electrophoresed and transferred on to Biodyne A nylon membrane. Transcript levels of TLR4 and actin were detected using biotin-labeled cDNA probes. (C) BAL macrophages were collected from WT, PU/ER(T)^+/−, and PU/ER(T)^+/+ bone marrow chimera mice on the 45th and 55th day (before and after clearance of circulating tamoxifen), and protein lysates were prepared. Expression of TLR4 protein in alveolar macrophages was determined by Western blotting analysis. Blots presented in panels B and C are representatives of samples analyzed from each group (n = 4).